At present, during the resin-coating phase (injection of filler material) and before the installation of the sealing piece that forms a cable guide (plug or hermetic hood and without vent holes), it is necessary to let in, during the resin coating, a rather large amount of air that is difficult to quantify in a repeated manner into the housing so as to allow the complete insertion of the sealing piece (airtight closure).
This solution exhibits the drawback of allowing a rather large amount of air into the inside volume of the housing.
As a result, and instead of ending in a total coating of the electronic components, the presence of this air in the device causes environmental changes, which can in particular induce risks of damage or deterioration of components and/or defects of electrical insulation.
In addition, it is often advantageous for this type of device to be able to visually indicate a state or their state from among several possible states (detection, absence of detection, malfunction, . . . ) by a light display that is visible at the housing.
The installation of the signaling means on the housing or their integration within the wall of the housing is problematic, taking into account mounting conditions and environments in which these devices are used.
Actually, in these known embodiments, the light element is at least in part projecting relative to the housing and requires the installation of an additional transparent protective means (cap or cover). This exposure to the outside environment, possibly aggravated by a prominence relative to the housing, of the light element is extremely unfavorable: limited options for installation, exposure to impact, exposure of the power supply line in the event of detachment, modification of the space requirement and the outside shape of the housing.
A known solution can consist in mounting the light sources of the signaling means inside the housing and in transmitting the light information for signaling through the transparent or translucent sealing piece.
However, this solution is not very effective (diffusion of light, low illumination and little visibility over the entire piece, plug that is necessarily entirely transparent or two-material) and/or requires specific additional pieces when the light element is not in the immediate vicinity of the sealing piece (light guide).
Nevertheless, the result is then the necessity for a specific positioning of the light guide(s) relative to the source(s) and the specific development of (a) guide(s) that is/are suitable for the above-mentioned type of devices, with the obligation not to interfere with the specific positioning and the good coating of the card and to preserve the integrity and the sealing of the device.
In addition, the document U.S. Pat. No. 6,025,562 discloses different embodiments of an electronic device of the above-mentioned type and a process for the production of such a device.
In a first embodiment, described in relation to FIG. 35 of this document and constituting the state of the art for the teaching of said document, a tubular housing that contains the detection element receives a first quantity of a first resin, and then a second quantity of a second resin. Next, a closing piece, forming a clamp and through which the connecting cable passes, is installed, and then additional quantities of the second resin are successively injected through the passage opening of the cable. This closing piece comprises a portion of transparent wall, but does not comprise a second opening for the injection of resin.
In the different variant embodiments of a second embodiment that is disclosed by the document U.S. Pat. No. 6,025,562, emerging from FIGS. 1 to 30, the housing that contains the detection element is sealed by a closing piece that forms a clamp and through which the cable passes. The inside volume of the unit is filled with resin by injection through a secondary opening that is provided in the closing piece. However, this secondary opening is not sealed by a connected plug but by the injected material (undefined finishing and outward appearance). A light-conducting portion can be integrated in the closing piece (FIG. 8), in line with the first embodiment disclosed by U.S. Pat. No. 6,025,562.